Thanks to https://github.com/serge-sans-paille/frozen
By default, Frozen is used if the compiler support C++14. It can be disabled by
using the "LIEF_DISABLE_FROZEN" option during the CMake configuration
step
* JSON visitor are located in the format namespace
* Visitor are *real* visitor
* Visitable class has been renamed to Object
* Due to a bug in Visual Studio 2015, we move to VS2017